Anadigi Boiler Control Cuts Operating Overheads
Factories rely heavily on steam generation for their production line heating requirements. However, traditional boiler control systems often contribute significantly to operating costs due to inherent inefficiencies and the need for constant operator intervention. These inefficiencies frequently lead to excessive water and coal consumption. Additionally, maintaining conventional boiler control systems requires specialized parts that are typically only available from the original manufacturer.
The Need for Greater Efficiency
According to Keith Gross of Anadigi, a smoking factory chimney stack is a clear indication of inefficient combustion and coal wastage. With a focus on optimizing productivity and reducing overhead costs, Anadigi recently implemented a more efficient boiler control system at a leading South African fast-moving consumer goods (FMCG) factory.
The factory engineer sought to automate the main factory boiler to enhance combustion efficiency and minimize coal and water usage. The new system was designed to use the steam pressure set-point as the primary control metric, ensuring that only the necessary amount of coal is consumed.
Advanced Automation Technology
Anadigi was contracted to design and install a simplified, versatile control system upgrade. Since the factory already operated with LS PLCs and VFDs, LS iS5 inverters were chosen to regulate the ID and FD fan speeds, while an iG5A inverter controlled the stoker speed.
Fan speeds are adjusted based on feedback from the steam set-point and the settings of the photo-helic pressure differential controller. The stoker conveyor speed is also integrated into this control strategy to ensure efficient fuel usage.
To accurately measure coal consumption, an IMO i3 PLC monitors the coal feed rate and reports usage in tons per hour. The built-in touch-screen HMI displays real-time coal usage data for easy monitoring. Additionally, the system includes a GSM dial-up feature for remote fault reporting.
The start-up process was also simplified. Initially, the boiler starts in manual mode to ensure that all safety interlocks are met. Once the boiler pressure reaches the required level and safety conditions are satisfied, the system automatically switches to automated control.
Impressive Results
The upgraded control system has delivered remarkable improvements. Over-pressure steam blow-off has been virtually eliminated, leading to significant reductions in both water consumption and coal usage.
The transition to automated boiler control has been well received, although some operators initially resisted the change. “The biggest challenge has been preventing operators from switching back to manual mode,” says Gross. “Many assumed that when the boiler enters sleep mode, they needed to adjust the coal feed rate manually. However, the system is designed to manage this automatically.”
Following the success of the Western Cape implementation, four additional boilers have been upgraded at the company’s Gauteng facilities, further enhancing efficiency and cost savings.